Electric heater for heating compressible fluids



R. J. WERT ELECTRIC HEATER FOR HEATING COMPRESSIBLE FLUIDS 2Sheets-Sheet 1 Filed Nov. 2, 1964 I N VEN TOR KOBEPTIA wan Aug. 29, 1967R. J. WERT 3,339,060

ELECTRIC HEATER FOR HEATING COMPHESSIBLE FLUIDS Filed Nov. 2, 1964 2Sheets-Sheet 2 k 755 I L 75 L74 L74 I 1 J0 Jo o INVENTOR BY i 241DUnited States Patent Ofi ice 3,339,060 Patented Aug. 29, 1967 3,339,060ELECTRIC HEATER FOR HEATING COMPRESSIBLE FLUIDS Robert J. Wert,Chattanooga, Tenn., assignor to E. I. du

Pont de Nemours and Company, Wilmington, Del., a

corporation of Delaware Filed Nov. 2, 1964, Ser. No. 408,093 1 Claim.(Cl. 219-364) ABSTRACT OF THE DISCLOSURE Apparatus for heatingcompressible fluids used to bulk yarn by passing the fluid through aplurality of passageways in a heat exchanger. A continuously energizedbase load heater is located at one side of each of the passageways. Anintermittently energized sWing load heater is located at the other sideof each of the passageways. The operation of the swing load heaters iscontrolled by control means responsive to the temperature of the heatexchanger. The end position swing load and base load heaters on the heatexchanger are energized at a higher voltage than the intermediateposition swing load and base load heaters to compensate for heat lossesat the ends of the heat exchanger.

This invention relates to an apparatus for heating compressible fluidsused in the production of bulked yarns, the yarns being produced byfeeding a yarn composed of a plasticizable polymer through a heatedturbulent stream of fluid.

As described in British Patent Nos. 905,895 and 941,-

931, the temperature of the compressible fluid is critical to thebulking process and must be closely regulated since there is acorrelation between bulking position temperature and yarn dyeability.Also, it has been discovered that heat losses occur at the end positionsof the heat exchangers which results in undesirable dye variations ofthe bulked yarn heated by the end positions as opposed to theintermediate positions. Accordingly, an object of this invention is toprovide an improved" apparatus for heating compressible fluid used inthe production of bulked yarns. Another object is to provide an improvedapparatus to compensate for heat losses at the end positions of the heatexchanger thus improving yarn dye uniformity. Other objects will appearhereinafter.

The objects of this invention are accomplished by an apparatus forheating compressible fluid used to bulk yarns which comprises, ingeneral, a heat exchanger having a plurality of separate, co-planarpassageways therethrough, means to supply compressible fluids to thepassageways, a swing load heater on one side and a base load heater onthe other side of each of the passageways, voltage source meansconnected to each intermediate heater, first switch means connectedbetween the voltage source means and the intermediate swing loadheaters, transforming means connected to the voltage source means tosupply both the end position swing load and base load heaters with apredetermined voltage greater in magnitude than the voltage supplied bythe voltage source means, second switch means connected between thetransforming means and the end position swing load heaters, measuringmeans responsive to the temperature of the heat exchanger and controlmeans responsive to the output of the measuring means to close the firstand second switch means when the output of the measuring means fallsbelow a predetermined point and to open the switch means when the outputexceeds the predetermined point.

The embodiments of this invention and their advantages can be morereadily understood by referring to the accompanying drawings.

FIGURE 1 is a schematic diagram showing an embodiment of the invention.

FIGURE 2 is a schematic diagram showing the relationship between a yarnbulking jet and the heat exchanger.

FIGURE 3 is a block diagram showing the use of the heat exchangers witha recorder controller.

Referring to FIGURE 1, there is shown heat exchanger 10 having separate,co-planar passageways 12, 14, 16, 18, 20 and 22 therethrough. Manifold24 is connected to the aforementioned passageways on one side of heatexchanger 10 and a source of compressed air (not shown) under apredetermined pressure is supplied to manifold 24 in the form of astream of high velocity air 26. Electric cartridge heaters 28, 30, 32,34, 36, 38, 40, 42, 44, 46, 48 and 50 are contained in heat exchanger 10and arranged so that one heater is adjacent to each side of a passagewayand in line with the axis of the passageway. Intermediate heaters 32,36, 42 and 46 (termed base load heaters) are connected directly to linevoltage 52 and are energized at all times when the power is on. Forexample, intermediate heater 32 is connected to lead 68 with lead 68tied to the line voltage 52 by means of lead 77. For the sake ofsimplicity the heater circuit return paths to line voltage 54 are notshown in FIGURE 1. However FIGURE 2, which shows the return path to linevoltage 54 for heaters 28 and 30, is illustrative of the return path forall the heaters. The remaining intermediate heaters 34, 38, 40 and 44(termed swing load heaters) are also connected to line voltage 52through conventional relay contacts C2; for example, heater 34 isconnected to lead 70 with lead 70 connected to voltage source 52 throughlead 76 and relay contacts C2. A variable transformer 56 is connectedacross line voltage 52 and 54. End position heaters 28 and 50 (termedbase load heaters) are connected directly to adjustable lead 58, ontransformer 56, through leads 79, 60 and 62. End position heaters 30 and48 (termed swing load heaters) are connected to lead 58 through leads64, 66, 78 and relay contacts C1. A thermocouple 74 is connected to heatexchanger 10 and conventional recorder controller 72. A precisionvariable resistor 80 is connected between recorder controller 72 andthermocouple 74.

FIGURE 2 illustrates the use of the novel apparatus of this invention tobulk yarn. As can be seen, only an exemplary part of heat exchanger 10is illustrated. Yarn theradline 84 is passed through a jet 82. The jetis connected to passageway 12 in heat exchanger 10. A source ofcompressed air 26 is supplied through manifold 24 to heat exchanger 10where it is heated in passageway 12 by means of end position heaters 28and 30. The heated air then passes into jet 82 for yarn bulkingpurposes.

With reference to FIGURE 3, there is shown a block diagram illustratinghow the novel apparatus of this invention is utilized commercially. Aplurality of heat eX- changers are serially connected to a singlerecorder controller. In practice, up to about 24 heat exchangers can beused to accommodate the yarn from a conventional drawtwister. Asillustrated each heat exchanger 10 has a precision variable resistor 80which is connected in the line between thermocouple 74 and recordercontroller 72.

In operation, thermocouple 74 measures the temperature of heat exchanger10 and sends a signal to recorder controller 72. Whenever thetemperature falls below a designated set point, the recorder controllerthrough conventional relay circuitry (not shown) closes contacts C1 andC2 thereby energizing swing load heaters 30, 34, 38, 40, 44 and 48. Ashereinbefore mentioned, base load heaters 28, 32, 36, 42, 46 and 50remain on at all times. After the temperature exceeds the set point, thecontroller turns off the swing load heaters by opening contacts C1 andC2. In this manner the temperature measured by the thermocouple isclosely maitained at a given point. End position heaters 28, 30, 48 and50 are connected to variable transformer 56 which supplies apredetermined higher voltage to these positions, thereby providinghigher heat input to compensate for the heat losses at end positions 12and 22 and thus reducing the differential in dye depth of the bulkedyarn between the various positions of each heat exchanger from 10.3% to2.5% as shown in the eX- perimental data of Table I. The yarn tested wasa 105 denier nylon yarn.

In addition, a variation in temperature among the heat exchangers on abulking machine can exist because of small differences in fit andpositioning of thermocouple 74. To insure that the dyeability of thebulked yarn from each heat exchanger is similar to that from every otherheat exchanger these temperature differences are minimized by installinga precision variable resistor 80 in the thermocouple circuit for eachheat exchanger. The thermocouples 74 are individually calibrated byadjusting their resistors 80 and in this manner the temperature at whichthe recorder controller 72 will operate is p edetermined for each heatexchanger.

With respect to the preferred embodiment, it i preferred that thecompressible fluid be compressed air and that the heat exchanger be madeof copper. However, the fluid may also be steam or any other vaporcapable of exerting a plasticizing action on the material of the yarn.Similarly, the heat exchanger may be made of any conductive metal, alloyor substance which can accommodate heaters that must heat thecompressible fluid to a temperature such that the temperature of theyarn to be bulked is in the range of the melting point of the yarn.

Referring to other elements utilized in the novel apparatus of thisinvention, many difierent types of elements can be used. For example,the recorder controller can be of any conventional design. The relaycircuitry can similarly embody any conventional design, such as an airsolenoid.

Although Table I illustrated the elfects of the use f this invention ona nylon yarn, it should be obvious that the use is not so restricted.The novel apparatus of this invention can be advantageously utilized toheat compressible fluids to, in turn, heat any yarn of a thermoplasticmaterial which is to be bulked in a process such as is disclosed inBritish Patent No. 905,895. For example, the thermoplastic material maybe polyamides, e.g., poly-(e-caproamide) and poly(hexamethyleneadipamide); polyesters, e.g., terephthalate esters of ethylene glycoland of trans-p-hexahydroxylylene glycol; polyalkylenes, e.g.,polyethylene and polypropylene; polyvinyls and polyacrylics, e.g.,polyacrylonitrile, as well as copolymers thereof.

Since many different embodiments may be made without departing from thespirit and scope of this invention, it is understood that the inventionis not limited to this specific illustration except as defined in theappended claim.

What is claimed is:

An apparatus for heating compressible fluids used to bulk yarn whichcomprises a heat exchanger having a plurality of separate colanarpassageways therethrough, means to supply compressible fluids to each ofsaid passageways, a swing load heater on one side and a base load heateron the other side of each of said passageways, voltage source meansconnected to each intermediate heater, first switch means connectedbetween said voltage source means and the intermediate swing loadheaters, transforming means connected to the said voltage source meansto supply the end position swing load and base load heaters with apredetermined voltage greater in magnitude than the voltage supplied bysaid voltage source means, second switch means connected between saidtransforming means and the end position swing load heaters, measuringmeans responsive to the temperature of said heat exchanger and controlmeans responsive to the output of said measuring means to close saidfirst and second switch means when the output of said measuring meansfalls below a predetermined point and to open said first and secondswitch means when the output exceeds the predetermined point.

References Cited UNITED STATES PATENTS 1/1930 Gaire 219--376 X 57-34 A.BARTIS, Primary Examiner.

